package com.heima.sample;

import org.apache.kafka.common.serialization.Serdes;
import org.apache.kafka.streams.KafkaStreams;
import org.apache.kafka.streams.KeyValue;
import org.apache.kafka.streams.StreamsBuilder;
import org.apache.kafka.streams.StreamsConfig;
import org.apache.kafka.streams.kstream.KStream;
import org.apache.kafka.streams.kstream.TimeWindows;
import org.apache.kafka.streams.kstream.ValueMapper;

import java.time.Duration;
import java.util.Arrays;
import java.util.List;
import java.util.Properties;

public class KafkaStreamQuickStart {
    public static void main(String[] args) {
        //kafka的配置中心
        Properties props = new Properties();
        props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "192.168.88.2:9092");
        props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass());
        props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass());
        props.put(StreamsConfig.APPLICATION_ID_CONFIG, "streams-quickstart");
        //stream构建器
        StreamsBuilder streamsBuilder = new StreamsBuilder();
        //流式计算
        streamProcessor(streamsBuilder);
        //创建KafkaStream对象
        KafkaStreams kafkaStreams = new KafkaStreams(streamsBuilder.build(),props);
        //开启流式计算
        kafkaStreams.start();
    }

    /**
     * 流式计算
     * 消息的内容:hello kafka
     * @param streamsBuilder
     */
    private static void streamProcessor(StreamsBuilder streamsBuilder) {
        //创建kstream对象，同时指定从那个topic中接收消息
        KStream<String,String> stream = streamsBuilder.stream("itcast-topic-input");
        //处理消息的value
        stream.flatMapValues(new ValueMapper<String, Iterable<String>>() {
            @Override
            public Iterable<String> apply(String value) {
                List<String> list = Arrays.asList(value.split(" "));
                System.out.println(list);
                return list;
            }
        })      //按照value进行聚合处理
                .groupBy((key,value)->value)
                //时间窗口
                .windowedBy(TimeWindows.of(Duration.ofSeconds(10)))
                //统计单词个数
                .count()
                //转换为kstream
                .toStream()
                .map((key,value)->{
                    System.out.println(key+":"+value);
                    return new KeyValue<>(key.key().toString(),value.toString());
                }).to("itcast-topic-output");
    }
}
